Portable fluid heater



Dec. 23, 1969 R LAHR ETAL 3.485,245

PORTABLE FLUID HEATER Filed June 21, 1967 T 2 Sheets-Sheet 1 INVENTORS.

ROY J. LAHR ARTHUR L. NIX, JR. HERBERT I. TERWILLIGER ATTORNEY.

2 Sheets-Sheet 2 R. J. LAHR ETAI- PORTABLE FLUID HEATER In N Dec. 23,1969 Filed June 21, 1967 United States Patent O 3,485,245 PORTABLE FLUIDHEATER Roy J. Lahr, Penfield, N.Y., and Arthur L. Mix, Jr., and HerbertW. Terwilliger, Lexington, Ky., assignors to International BusinessMachines Corporation, Armonk, N.Y., a corporation of New York Filed June21, 1967, Ser. No. 647,814 Int. Cl. A61j 1/00; F28f 7/00; A6lf 7/00 US.Cl. 128-272 Claims ABSTRACT OF THE DISCLOSURE An apparatus for heatingfluids to the correct body temperature prior to their intravenousinjection. The fluid flows from its cold storage container throughtubing to a sterile, disposable, heat conductive, fluid imperviouspouch, and from the pouch through tubing to the patient. The pouch isclamped within conduit defining heating platens which heat the fluid asit passes through the pouch in a defined path. Temperature sensing meanslocated in the heating unit and an automatic control device insure thecorrect fluid temperature. When the injection is complete, the pouch isremoved from the heating platens and a new pouch installed forsubsequent operation.

BRIEF BACKGROUND OF THE INVENTION Field This invention relates to animproved fluid heater for heating fluid for intravenous injection, andmore particularly to a fluid heater which can rapidly heat a fluid fromits cold storage temperature to a temperature compatible with humaninjection and which can be thereafter utilized for another patient witha minimum of delay.

Description of prior art The present fluid heater is designed for use infield situations where blood transfusions are necessary on anunpredictable schedule and where the blood transfusion must beadministered as quickly as possible.

Blood plasma is generally stored in cold storage at about 40 degreesFahrenheit. In order to inject blood plasma into a human, it isnecessary to heat the blood plasma from its cold storage temperature to95 to 100 degrees Fahrenheit (the approximate body temperature of thehuman). The prior are fluid heaters fall into two general categories.One type of fluid heater heats the entire volume of fluid to beadministered to the patient. In its most elemental form, this type offluid heater comprises a kettle ofwater maintained at a fixedtemperature in which is dropped a sealed container containing the fluidto be administered. The sealed container can be a bottle,'plastic bag,or other well known blood storage device. More sophisticated devicesutilize electrical heating elements which are adapted to surround thefluid containing memher and temperature sensing devices to determinewhen the fluid has reached the cor-rect temperature. In either instance,it is necessary to heat the entire volume of fluid to be administered tothe correct temperature prior to its administration. While such fluidwarmers are satisfactory in non-emergency situations where it has beenpreviously determined that the fluid will be required, they are notreadily adaptable to emergencies or unpredictable situations where itisnecessary to administer the fluid as quick- 1y as possible. v i

The second prior art approach is to heat the fluid as it is beingutilized. Devices which accomplish this generally comprise elongatedtubular members through which the fluid flows. Surrounding the tubularmember are heating elements and temperature sensing devices which causethe fluid flowing through the tubular member to be heated 3,485,245Patented Dec. 23, 1969 to the correct temperature at its exit pointwhereupon it is applied to the patient. While such devices provesatisfactory for emergency situations, they are not readily adaptablefor reuse. In order to reuse such a device, it is necessary to insurethat all of the fluid from a previous intravenous injection has beenremoved from the tubular member prior to introducing the fluid to beinjected into a second patient. It is also necessary to insure that thetubing and containers are sterile. Thus, once such a device has beenutilized, it may not again be reused until it has been thoroughlycleansed. Such devices are not practical where it is necessary to treata plurality of patients within a short time period.

SUMMARY In order to overcome the above problems of prior art and toprovide a portable fluid heater which can rapidly heat fluid from itscold storage condition to a temperature compatible with human injectionand which can be reutilized for a plurality of patients withoutnecessitating cleansing or sterilizing procedures, the fluid heater ofthe present invention is provided with a novel, sterile, disposable,fluid impervious heat conductive pouch which is clamped within a conduitdefining heating member.

The fluid to be administered is introduced into the pouch from the coldstorage container through a disposable sterile tube which is insertedinto the pouch. The conduit defining heating member causes the fluid topass through the pouch in a predetermined path to an exit point. As thefluid passes through the pouch, it is heated by the conduit definingheating member to be at the correct temperature when it exits from thepouch. Since it is necessary that the fluid be at the correcttemperature only at the exit point, it is unnecessary to first heat theentire volume of fluid in the pouch to the correct temperature prior toinjecting the fluid. A second disposable tube is inserted into the pouchat the exit point and serves to connect the pouch with the patient.

When the injection is complete, the pouch and the tubing are disposedof, a new pouch is inserted into the conduit defining heating member,and the portable fluid heater is then ready to be reused.

The foregoing and other features and advantages of the invention will beapparent from the following more particular description of the preferredembodiment of the invention as illustrated in-the accompanying drawings.

In the drawings:

FIGURE 1 is a top perspective view of the portable fluid heater.

FIGURE 2 is a cross-sectional side view of the fluid heater of FIGURE 1showing a conduit forming heating platen.

FIGURE 3 is a side view of the disposable pouch and its associatedtubing as it would appear when filled with fluid andlocated between theconduit forming members of the heater of FIGURE 1.

FIGURE 4 is an exaggerated partial cross-sectional viewof the disposablepouch of FIGURE 3.

FIGURE 5 is a schematic diagram of an electronic automatic controldevice which can be utilized to insure that the fluid reaches thecorrect temperature for injec tion.

The portable fluid heater of the present invention consists of twoparts, a permanent heating unit and a disposable pouch. The pouch isadapted to fit within the heating unit and contain the fluid. Theheating unit heats the fluid in the pouch and additionally, defines thepath which the fluid takes through the pouch. Referring now to FIGURE 1,there is shown a top perspective view partially in section of theheating unit. The heating unit .11 is shown as a box-like structurehaving a front panel 13, side panels 15 and 17, a back panel (notshown), a bottom panel (not shown) and top panels 19 3 and 21. Thepanels are joined to one another by fasteners 23. Joined to the heatingunit 11 is a structure 25 which contains the electrical circuitsnecessary to regulate the fluid heating.

Adjustable clamping screws 27 and 29 are threadably mounted through thefront panel 13 and engage a movable wall 31. Rotation of the clampingscrews causes the movable wall 31 to move in a direction perpendicularto the front panel 13. The movable wall 31 has four heating elements32-33 mounted thereon. Spacing members 35 and 37 are fixedly attached tothe two heating elements 32 and to a conduit forming member 39. Movementof the movable wall 31 thus results in corresponding movement of theheating elements 32 and 33, spacing the members 35 and 37, and theconduit forming member 39. In addition to forming a mechanicalconnection, the spacing members 35 and 37 cause the conduit formingmember 39 to be spaced away from the heating elements 32 and 33 toinsure an even distribution of heat in the conduit forming member whichis made of a heat conducting material such as aluminum.

A complementary conduit forming member 41 is mounted in a similar mannerto a spacing member 43 and to a spacing member not shown. The spacingmembers are mounted to heating elements 45 which along with heatingelements 46 are fixedly mounted to a stationary wall47.

The conduit forming member 41 has located therein a continuous channel51-53 which has been hollowed out of the solid member. The conduitforming member 39 has a complementary continuous channel 55-57 locatedtherein. Referring now to FIGURE 2, a cross-sectional side elevationview along lines 2-2 of FIGURE 1 shows the conduit forming member 41resting upon the bottom panel 60. As can be seen, the elongated channel51-53 is continuous and winds throughout the conduit forming member.Channel 55-57 of the conduit forming member 39 shown in FIGURE 1 is themirror image of the channel 51-53 and it complements the channel 51-53to form a conduit which is oval or circular in cross section when thetwo conduit forming members are brought together.

Referring once again to FIGURE 1, the heating unit 11 is depicted asbeing of relatively rugged construction in order to facilitate a fielduse such as battlefield use. The outer panels 13, 15, 17, 19, 21, 60(FIGURE 2) and the back panel (not shown) of the heating unit 11 can bemade of a durable material, such as, for example, rolled steel. Themovable wall 31 and the stationary wall 47 can also be made of the samematerial. The spacing members 35, 37, and 43 are preferably made of aheat resistant insulating material such as asbestos while the conduitforming members 39 and 41 are made of a heat conducting material such asaluminum. The heating elements are commercially available electricalresistance heating units.

In operation, the adjustable clamping screws 27 and 29 are rotated in adirection to cause their movement to be away from front panel .13. Sincethe clamping screws are attached to the movable wall 31, withdrawal ofthe clamping screws causes the movable wall 31 and the forming member 39which is mechanically coupled thereto to move toward the front panel 13and away from the conduit forming member 41.

The resulting separation of the conduit forming members 39 and 41 leavesa void in which a pouch filled with fluid (see FIGURES 3 and 4) isinserted. The top plates 19 and 21 are separated by a sufficientdistance to allow the pouch to be inserted therebetween. Once the pouchis so located between the conduit forming members 39 and 41, theadjustable clamping screws 27 and 29 are tightened down causing themovable wall 31 and conduit forming member 39 to move toward the conduitforming member 41. Movement of the conduit forming member 39 traps,clamps, and embraces the pouch be- 4 tween the conduit forming membersand causes the fluid located within the pouch to conform to the shape ofthe conduit thus formed.

Referring now to FIGURES 3 and 4, a pouch 61 is shown as it would appearwhen clamped between the two conduit forming members ofjFl GURE l. Thepouch 61 is made of a thin (2 mils nominal) metal foil layer 63, theinner surface of which is coated with a thin plastic coating 65 which iscompatible with the temporary storage of blood. The metal foil 63utilized should have good heat transfer characteristics and be flexiblewhile the plastic coating 65 must be thin enough so that the pouch hassuperior heat transfer characteristics, For example, the metal foilcould be aluminum foil and the plastic coating could be polyethylene.

Two rubber-like plugs 67 and 69, similar to those utilized on medicalvaccine bottles, are inserted into the uppermost surface 71 of the pouch61 and serve as connector points which define the entrance and exitports of the pouch. When ready for use, hollow needles 73 associatedwith sterile tubing 75, 77 may be inserted into the rubber-like plugs67, 69. Thereafter, fluid can flow from a supply (not shown) throughtubing 75 to the pouch 61, then through tubing 77 to the patient (notshown). The path that the fluid takes through the pouch is determined bythe conduit forming members of FIG- URE 1 and is denoted as conduit79-81 in FIGURE 3.

When manufactured, the interior plastic coating of the pouch issterilized and all edges of the pouch except uppermost surface 71 areheat sealed. A measured quantity of sterile fluid 83 such as salinewater, glucose water solution, or other human blood compatible fluid isinserted into the pouch through the opening in uppermost surface 71. Therubber-like plugs 67, 69 are then put in place and the uppermost surface71 is sealed. The fluid 83 serves to hold the pouch 61 in shape andforces the pouch to conform with the channeled surfaces of the conduitforming members when placed in use. The fluid excludes air from thepouch and can also be utilized when the pouch is placed in use to removeair from the connector tubing 75, 77.

Referring once again to FIGURE 1, the heating elements 32, 33, 45 and 46must be supplied with a suflicient amount of electrical energy to heatthe fluid to its proper temperature. The amount of electrical energysupplied depends upon the rate of flow of the fluid, upon the efficiencyand heat transfer characteristics of the device, and upon the coldstorage temperature of the fluid. Assuming a flow rate of /2 pint offluid per minute, a 50% heat transfer efficiency, a fluidinputtemperature of 5 C. and a fluid exit temperature of 40 C., it has beenfound that a 1200 watt heating circuit will supply the requisite heat.

Of course, the cold storage temperature of the fluid and efiiciency ofthe device vary from situation to situation thereby necessitating anautomatic control device to regulate the heat dissipated by the heatingelements and to thereby insure that the fluid exits at the propertemperature, Many types of automatic control devices could be utilized.Structure 25 is shown for housing such a device.

In the embodiment illustrated, two temperature responsive elements 101,103 are embedded in conduit forming member 41 (see FIGURE 2) with onepreferably located near the conduit exit and the other located near thecenter of the conduit forming member.

Referring now to FIGURE 5, there is shown a schematic diagram of anelectronic automatic control device utilized to regulate the amount ofheat imparted to the fluid to be warmed. Alternating current is suppliedto terminals 104 and 105. Switch 106 allows for ready operator controland fuse 107 prevents circuit overload. Load 109 represents the heatingelements shown in FIGURE 1. The remaining circuitry shown in FIGURE 5located within blocks 111 and 113 controls the amount of currentavailable at terminals 104 and that will be utilized by the load 109.The circuitry located within block 111 is identical to that locatedwithin block 113, one block controlling the amount of current utilizedduring the positive half cycle of the alternating current input whilethe other controls the current utilized during the negative half cycle.

The circuitry in block 111, which is operative during positive halfcycles to regulate the current delivered to the load 109 comprises acontrol transistor 115 which is turned on and off by positive andnegative going pulses respectively. When the transistor 115 is on, thecurrent flowing through its emitter gates a silicon control rectifier(SCR) 116. When the SCR 116 is on, a current path is provided throughthe SCR from terminal 104 through the load 109 to terminal 105 duringpositive half cycles. The point in time during the positive half cyclethat the control transistor 115 turns on determines the length of timethat current will flow through the load 109 during the positive halfcycle. This in turn is determined by the voltage appearing on baseelectrode 117 of the transistor.

The voltage at the base electrode 117 of the transistor 115 is afunction of the values of the resistor 119 and the variable resistor 121which form a series connection from the fuse 107 to the base electrode117 and the resistive value of the temperature responsive element 101which is connected to the base electrode 117 to form a voltage dividernetwork with the resistors 119 and 121.

The variable resistor 121 is set in accordance with the value of theinput voltage appearing across terminals 104 and 105 and in accordancewith the desired output temperature. Once this resistor is set, thevoltage appearing at the base electrode 117 becomes a function of theresistive value of the temperature responsive element 101, The resistivevalue of the temperature responsive element decreases when itstemperature increases and increases when its temperature decreases. Thisaction causes the control transistor to conduct for a shorter timeperiod when the temperature of the temperature responsive element 101 isrelatively high and for a longer time period when the temperature isrelatively low.

A thermal control 123 and a resistor 125 are connected in series andshunt the temperature responsive element 101. When the temperature ofthe device exceeds a predetermined maximum, the thermal control 123closes and forms a low resistance shunt path to the temperatureresponsive element 101 thereby biasing the control transistor 115 out ofconduction. This device thus forms a safety feature which preventsoverheating in case there is a malfunction in the voltage dividernetwork or in the temperature responsive element 101.

A capacitor 126 connected between resistor 119 and the load 109 forms anRC network with the resistor 119 to integrate the input sine wave toallow control of the SCR 116 through a high percentage of its halfcycle. A diode 127 and resistors 129 and 131 connected to the collectorelectrode of the control transistor 115 provide a DC bias for thecontrol transistor. A resistor 132 is connected between the emitterelectrode of the transistor 115 and load 109.

The circuitry appearing in block 113 is a duplicate of that in block 111and operates during the negative half cycles to control the amount ofcurrent supplied to the load 109. This circuitry includes temperatureresponsive element 103.

Typical operating values are shown in the following table:

Voltage at terminals 104, 105 117 volts AC. Resistor 119 K.

Resistor 121 10K.

Resistor 125 100 ohms. Capacitor 126 1 microfarad. Resistor 129 39 K.

Resistor 131 1K.

Resistor 132 1K. Temperature sensitive element 101 100 ohms to 1K.

It is of course recognized by those skilled in art that many suchcontrol devices could be utilized in accordance with the circumstances.In the particular embodiment shown, it has been assumed that an ACsupply of approximately 117 volts is available. A control circuitresponsive to DC voltages could also be utilized.

Further, the mechanical construction of the heating unit can be Widelyvaried. For example, the heating platens could be hingedly connected andoperate in the manner that a waflle iron does. Also, the pouch couldpartially extend from the confines of the heating platens.

While the invention has been particularly shown and described withreference to a preferred embodiment thereof, it should be understood bythose skilled in the art thatthe foregoing and other changes in form anddetail may be made therein without departing from the scope of 'theinvention.

What is claimed is:

' 1. A fluid heater comprising:

a fluid impervious flexible pouch having an entrance port and an exitport, the interior of said pouch being compatible with the temporarystorage of blood, the exterior of said pouch having good heat transfercharacteristics;

a first conduit forming member having an elongated channel locatedWithin one surface thereof;

a second conduit forming member for cooperatively embracing said fluidimpervious pouch between said second conduit forming member and saidfirst conduit forming member to effect the formation within said pouchof a continuous conduit leading from said entrance port to said exitport;

heating means for heating the pouch so embraced between said conduitforming members.

2. The portable fluid heater set forth in claim 1 wherein said first andsecond conduit forming members are made of heat conductive material andwherein said heating means heats said first and said second conduitforming members to thereby heat said pouch.

3. The fluid heater set forth in claim 1 further comprising:

temperature sensing means located closely adjacent to said pouch forindicating the temperature of said pouch;

control means responsive to said temperature sensing means to controlthe amount of heat supplied by said heating means.

4. The fluid heater set forth in claim 3 wherein said second conduitforming member having a second elongated channel located within onesurface thereof adapted to cooperate with the elongated channel of saidfirst conduit forming member to embrace said pouch and form a continuouschannel within said pouch leading from said entrance port to said exitport.

5. The fluid heater set forth in claim 4 wherein said second conduitforming member is adapted to cooperatively embrace the entire pouchbetween the first conduit forming member and the second conduit formingmember.

References Cited UNITED STATES PATENTS 1,995,302 3/1935 Goldstein 128254XR 2,760,630 8/ 1956 Lakso.

3,042,086 7/ 1962 Winchell 128214 XR 3,140,716 7/1964 Harrison et al.128214 XR 3,158,283 11/ 1964 Rinfret et a1 220-64 3,293,868 12/1966Gonzalez 46 XR 3,370,153 2/1968 Du Fresne et al. 128214 XR 3,411,63011/1968 Alwall et al. 210-321 RICHARD A. GAUDET, Primary Examiner M. F.MAJESTIC, Assistant Examiner US. Cl. X.R.

